Electric ladle furnace



v. H. FERGUSON snsc'ralc LADLE FURNACE Qct. 17, 1950 3 Sheeta-Sheet 1Original Fil od May 14, 1949 NHL IN V EN TOR.

Oct. 17, 1950 v. H. FERGUSON 2,525,883

susc'mc mm: FURNACE Original Filed May 14, 1949 3 Sheets-Sheet 2 Oct.17, 1950 i v FERGUSON 2,525,883

I ELECTRIC LADLE FURNACE Original Filed May 14, 1949 3 Sheets-Sheet 3 INVEN TOR.

IZTOZ/VEY I- Patented Oct. 17, 1950 ELECTRIC LADLE FURNACE Vernon H.Ferguson, Mount Lebanon, Pa., as-

signor to Loftus Engineering Corporation, a corporation of MarylandOriginal application May 14, 1949, Serial No. 93,243. Divided and thisapplication January 21, 1950, Serial No. 139,896

2 Claims.

My invention relates to furnaces, particularly to ladle furnaces for usein handling molten metal in foundries and other industrial shops.

A ladle furnace of the sort in mindconsists in a crucible for moltenmetal. The crucible is installed within a refractory-lined body orshell, with a space provided between the walls of the crucible and theshell for electrical heating elements (or for hot products ofcombustion) to heat and maintain the molten metal within the crucible atdesired temperature. The entire structure is adapted to be pivotallysupported by means of a bail that can be engaged by an overhead crane,or the like, and on such pivotal support the ladle structure is arrangedto be tilted, whereby molten metal may be poured or teemed from thecrucible as required.

My invention consists in certain new and useful structural improvementsin ladles or ladle furnaces of this type, to the end that thermalefficiency is obtained in largest measure, together with increasedeconomy and. durability of structure.

From time to time the crucibles of such ladles fail in service, with theresult that molten metal escapes into the space within therefractory-lined body or shell. This requires that the ladle structurebe taken out of service and the molten metal, then solidified, removed.This is the difiicult task, and in the case of electrically heatedladles, there is danger of destroying or damaging the heating elements.

In further accordance with the objects of my invention, I provide afalse bottom on the refractory-lined body or shell. This false bottom isarranged at an interval below the normal refractory-lined bottom of theshell, providing an auxiliary chamber. Passages are formed in the normalbottom of the refractory-lined body and these open into the auxiliarychamber, whereby molten metal (escaping due to the failure of thecrucible) runs into the auxiliary chamber where it is accumulated andsolidified. The false bottom is readily dismountable, for the removal ofthe solidified metal.

In the accompanying drawings a, ladle furnace comprising an exemplaryembodiment of the invention is illustrated in the drawings:

Fig. 1 is a view of the ladle furnace in front elevation;

Fig. 2 is a sectional view of the ladle furnace, as seen on the planeII-II of Fig. 1;

Fig. 3 is a diagrammatic view of a mechanism included in the structurefor manually tilting the ladle on its pivotal support;

Fig. 4 is a view in medial horizontal section through the ladle,illustrating a modification in structure;

Fig. 5 is a view partly in side elevation and partly in vertical sectionof a ladle embodying still other modifications in structure; and

Fig. 6 is a fragmentary view in vertical section, showing the lowerportion of the modified ladle structure of Fig. 5 to still larger scale.

Referring to the drawings, the ladle structure comprises an outer shell2, cylindrical in this case, formed of steel plate. Above the center ofgravity of the ladle structure, trunnions 3 are secured upon oppositesides of the shell in axial alignment, and to these trunnions a bail 4is attached, the bail having an eye 5 whereby the entire structure maybe engaged, lifted and transported by means of an overhead crane.

On one side of the ladle a, hand-wheel 6 is geared to the adjacenttrunnion 3, by means of which the ladle structure, when suspended from acrane, may be manually tilted, to pour or teem molten metal from a spoutl, as will presently appear. The gearing between the hand-wheel 6 andthe adjacent trunnion 3 consists in a wormgear 8, a worm 9, and twobevel gears I0 and II. The bevel gear I i is integral with the axis ofthe hand-wheel 6, and meshes with the bevel gear In which is rigidlymounted on a shaft l2 that carries the worm 9 meshing with the worm-gear8. It will be manifest that the rotation of the hand wheel in eitherdirection will effect rotation of the worm-gear 8 with great mechanicaladvantage, and, the worm-gear 8 being rigidly secured on the adjacenttrunnion 3 of the ladle, the ladle may be tilted as required. Theengagement of the teeth of the worm 9 with the teeth of the worm-gear 8serves as a, mechanical lock to prevent the tilting of the ladle fromany position into which the ladle is adjusted.

A refractory lining I3 is provided within the body or shell 2, therefractory lining or partition at the bottom of the body being borne ona plate 14 secured to an annulus l5 of angle shape in cross-section,welded to the steel plate which forms the outer shell of the structure.

In the refractory-walled chamber l6 thus provided, a crucible or pot I1is mounted, the body of the crucible being formed of refractory ceramicmaterial, or metal, dependin upon the nature of the metal to bemaintained in molten condition in the crucible. The crucible issupported on a stool l8 constructed of steel alloy or other suitableheat-resisting, heat-conducting material, in this case the stool beingformed of a 25% chrome-12% nickel steel alloy. It will be noted that thestool consists in an open ring portion 19, upon which the crucibleimmediately seats, and from said ring portion a plurality of spaced legsextend downward through the refractory floor of the chamber 15 to themetal plate 14 that forms the normal bottom wall of the chamber.

Over the top of the structure a refractory-lined metal cover 2| isremovably secured by means of screws 22.

The means for melting, heating and maintaining a charge of metal withinthe crucible I! in the desired molten condition consists in electricresistor elements 23 supported on insulators 25, which protrude inwardlyfrom the refractory wall or lining [3 into the space provided betweensuch lining and the wall of the crucible. Electrical cable 25 carriesfrom a suitable source electric current to the resistor elements 23, andin known way such elements are energized to generate the required heat.It will be noted that the stool is of open construction, providingapassage beneath the crucible. whereby the heat generated within thechamber [6 will be distributed and applied uniformly over all of thesurface areas of the crucible.

The refractory-lined body 2 is provided with a false bottom 26 which isspaced at an interval below the normal refractory bottom of te chamberi6. The bottom 26 consists of a heavy plate of steel welded to anannulus 2? of angle shape in cross-section, and is secured to the outershell 2 by means of removable screws 28 passing through the verticalflange of said annulus into threaded engagement with shell 2. Thisstructure provides an auxiliary chamber 29 below the chamber E6 in whichthe crucible is positioned. From the chamber l6 downwardly divergentpassageways 33 open into the auxiliary chamber 29. If and when thecrucible i7 cracks or wears through in service, the escaping moltenmetal quickly flows through the passages 39 into the auxiliary chamber29. In this way the molten metal does not accumulate in the chamber !8where it may contact and short-circuit the resistors Furthermore, if andwhen the crucible fails in service, the resistors 23 are de-energized toallow the structure to cool to the extent neces sary to insert a newcrucible. But for the iinprove-merits of my invention the escapingmolten metal would. accumulate solidify in the bottom of the cha-mbe i6.thereby presenting a difficult problem. However, in the structuredescribed, he molten metal (regardless of the deree of tilt of the ladlestructure when failure of the crucible may occur) runs into the chamberwhere it solidifies.

The fa se bottom 26 of the auxiliary chamber 25 comprises a removablewall section, it being merely necessary to remove the screws 28 andremove the false bottom and dislodge the accumulated metal. The ladlemay be quickly reconditioned for continued service.

In the case of certain metals, there may be a tendency for the metal tostick or adhere upon solidification to the walls of the auxiliarychamber 29. In prevention of this, the auxiliary chamber lined with arefractory and readily separable or frangible material, such as sheetasbestos 3i. When a mass of accumulated metal has been removed from theauxiliary chamber, the deciduous lining 31 may be readily renewed.

Such is the construction of a ladle furnace of my invention. She top 2|is readily removable for charging molten or pig metal into the crucibleIT, or for giving access to the internal parts of the structure forcleaning or repair. It is unnecessary to dwell upon the manner in whichthe ladle furnace is operated. Those skilled in the art will readilyunderstand. Sufiice it to say, that a batch metal may be melted andalloyed by the introduction of a suitable charge into the crucible, and,when in molten condition, the metal may be maintained at specifiedtemperatu're for the intended use.

While the ladle structure described above is arranged for elec ricalheating of the crucible, in modification the structure may be designedfor heating by means of a. fluid fuel. As shown in Fig. l, the chamber16 between the refractory lining iii of the outer body and the wall ofthe crucible ll may comprise a combustion chamber, and through the shell2 and refractory lining l3 one or more burners 32 may be directed,tangentially as shown in Fig. A mixture of gaseous or liquid'fuel andcombustion air may be delivered by the burners 32, and combustionmaintained in the chamber it at the desired rate, to heat and maintainthe metal in the crucible at proper temperature. The products ofcombustion may be vented through one or more ports 33 formed in the wallof the refractory-lined body of the ladle structure.

Whereas the ladle structure first described in the foregoingspecification is provided with electrical resistor elements mounted inthe space between the refractory wall of the ladle chamber and the wallof the crucible, in the modified structure of Figs. 5 and 6 the resistorelements 32a are embedded in refractory units 24a, and the leads fromthe resistor elements 23a are extended downward through the refractorybottom of the structure, ending in terminals 33 which are accessible inan annular raceway 35 (Fig. 6). Such organization of electric resistorelements within a refractory-supporting structure is old, and forms nopart of my invention, except in the features of organization of suchelements with the ladle structure in which they are described.

In the modifi d structure of Figs. 5 and 6, it will be noted that thecrucible Ila is supported upon the refractory bottom of the ladle body;that is, the legs 28a which carry the cruciblesupporting ring iSa ofheat-resisting alloy are fixed at their lower ends to a ring '5?) whichrests upon the refractory bottom.

The false bottom 250. (Fig. 6) is removably secured by screws 28a to anannulus 21a of angle shape in cross section. An angle-shaped annulus 35is welded to the lower edge of the shell 2a, and a plurality of verticallegs 31, also of angle shape in cross section, are welded to the annuli2ia and 3-6, whereby a rigid support is furnished for the false bottom26a.

A conical wall 38 is welded at its upper edge to the bottom plate 54a ofthe structure, and at its lower edge is welded to the inner periphery ofthe annulus 21 0. The auxiliary chamber 29a, which is adapted to receivrthe escaping molten metal in case of crucible failure, is formed by thebottom plate Ida, the conical or vertically extending wall 38 and thefalse bottom 26a. Between the annuli Zia and 35, an outer wall or coverplate 39 extends circumferentially of the ladle structure. The cover-plate 39 may be formed in sections, secured by means of screws 45 tothe angle members It will be perceived thatan annular raceway 35 is thusformed between walls 38 and 39, and between the bottom Eda of thecrucible chamber and the false bottom 26a and annulus 21, a racewaywhich is entirely enclosed, to form a housing for the electricalconductors (not shown) which connect the terminals of the resistors 23ato the contact members of a conventional plug-in receptacle 4|, by meansof which the electrical feeder lines for energizing the resistors may bereadily connected or disconnected. The enclosed raceway 35 may be openedfor inspection or repair of the electrical conductors and housedtherein, by merely removing the cover plate 39.

The auxiliary chamber 29a provides, as in the structure first described,a safe accumulation space for molten metal that escapes in the case offailure of the crucible. It is a simple matter to remove the falsebottom 26a and clean away the molten metal when it has solidified.

Within the terms of the appended claims various modifications andchanges in the ladle structure may be made by the mechanic without departing from the spirit of the invention.

The application to these Letters Patent comprised a division of myapplication Serial No. 93,243, filed May 14, 1949.

I claim:

1. A ladle furnace for molten metal comprising a crucible chamber havingside walls and a bottom lined with refractory material, a crucible formolten metal supported in said chamber, electrical means arranged withinthe refractory walls of said chamber for heating the crucible tomaintain the contents thereof in molten condition, an auxiliary chamberbelowsaid crucible chamber, said auxiliary chamber having an outerperipheral wall and a false bottom, an inner peripheral wall in saidauxiliary chamber spaced from the outer peripheral wall of such chamberand extending between the bottom of said crucible chamber and said falsebottom and forming between said outer peripheral Wall of said auxiliarychamber and said bottoms a raceway for electrical conductors, means forremovably securing said false bottom to the ladle structure, and a portopening through the refractory bottom of said crucible chamber into thespace Within said inner peripheral Wall in said auxiliary chamber.

2. The structure of the next-preceding claim wherein the outerperipheral wall of said auxiliary chamber comprises a cover plateremovable to give access to said raceway, and means for detachablysecuring said cover plate in assembly with the ladle structure.

' VERNON H. FERGUSON REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS 25 Number Name Date 723,6 l3 Bradley Mar. 24,.1903 1,686,610 Keene Oct. 2, 1928 1,922,034 Feehan Aug. 15, 19331,224,638 Claw-son 2. Aug. 29, 1933 39 2,039,165 Hayalrawa Apr. 28, 19362,294,03 Jaeger Aug. 25, 1942 2,363,582 Gerber et al Nov. 28, 19442,407,882 Hutchinson et al. Sept. 17, 1946 2,445,425? Roth can July 20,1948 35 2,473,095 Grene June 14, 1949

